The present invention relates to fluid pressure brake control systems for railroads, and it more particularly pertains to a fluid pressure brake control portion of such a system.
Weight distribution in intermodal articulated freight cars, such as is disclosed in the Engle U.S. Pat. No. 3,910,641, for example, generally loads intermediate trucks heavier than the end trucks. It is therefore desirable to use the same type of brakes on all trucks and modify braking pressures for the end trucks to be only a certain percentage, such as 60%, for example, of the braking pressure provided for the intermediate trucks. This modification can be accomplished by using the conventional empty-load brake equipment, such as is disclosed in the Engle and Scott U.S. Pat. Nos. 4,080,005 and 3,671,086 respectively.
These systems use changeover valves to sense weight on the trucks, but because the end trucks will always operate at the reduced pressure, the changeover devices do not need to be operated as only the empty setting is needed, so the weight sensing arms are removed, and the changeover valves remain in their empty positions to render proportioning valves always effective to provide 60%, for example, of the braking pressure for delivery to brake motors in the end trucks of the articulated vehicle.
An object of the present invention is to provide proportional braking pressure for end truck braking motors in a matter obviating some of the limitations of prior systems.
Another object of the present invention is to provide an improved and less costly proportional braking system for the braking motors of at least one truck of a railway vehicle.
Other objects, purposes and characteristic features, will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.